Synthesis and Structural Characterisation of Dinuclear Aluminium Complexes Supported by NNO‐Tridentate Schiff‐Base Ligands and Their Catalysis in the Ring‐Opening Polymerisation of ϵ‐Caprolactone

Abstract

AbstractIn this study, we prepared a series of dinuclear aluminium complexes {Bis{2‐OAlMe2‐3‐CH=N[CH2CH2N(CH3)2]‐5‐CH3C6H2}CH2, Bis[2‐OAlMe2‐3‐CH=N(2‐PyCH2)‐5‐CH3C6H2]CH2, and Bis{2‐OAlMe2‐3‐CH=N[2‐N(CH3)2C6H4]‐5‐CH3C6H2}CH2} as well as their corresponding mononuclear aluminium compounds derived from NNO‐tridentate Schiff‐base ligands. The compounds were characterised by 1H and 13C spectroscopy and elemental analyses. Complexes 4 and 7 were additionally characterised by single‐crystal X‐ray diffraction. Their activities toward the ring‐opening polymerisation (ROP) of ϵ‐caprolactone (ϵ‐CL) were investigated. In the presence of benzyl alcohol (BnOH), these complexes are catalytically active for the ROP of ϵ‐CL. The kinetic studies for the polymerisation catalysed by these complexes indicated that the polymerisation was well controlled and produced polymers within a narrow molecular weight distribution. At low monomer concentrations, the catalytic activity of binuclear complexes is considerably greater than that of mononuclear complexes.